Brake mechanism



Jan. 19, 1943. J MLCUNE 2,308,889

- BRAKE MECHANISM l Filed May 1, 1941.

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JOSEPH C. McCUNE ATTcXRNE'Y f v INVENTOR Patented Jan. 19, 1943 BRAKEMECHANISM Joseph C. McCune, Edgewood, Pa., assignor to The WestinghouseAir Brake Company, Wilmerding, Pa., a corporation of PennsylvaniaApplication May 1, 1941, Serial No. 391,224

(Cl. Gil-62.6)

12 Claims.

This invention relates to fluid pressure controlled motor devices andmore particularly to the single acting type such as brake cylinderdevices employed in fluid pressure brake systems.

In the copending application of Ellis E. Hewitt, Serial No. 253,316,filed January 28, 1939, issued as Patent No. 2,277,106 on March 24,1942, and assigned to the assignee of this application, there isdisclosed a brake cylinder device embodying a casing which is secured tothe outboard end of a journal box of the type employed in connectionwith railway vehicle trucks. This casing contains a brake cylinderpiston which is adapted to be moved in the direction of the journal boxby fluid under pressure for applying the brakes on the truck. A releasespring in the casing acts on the piston for moving same in the oppositedirection to a release position for releasing the brakes on the truckwhen the fluid under pressure is released from the brake cylinderdevice.

In order to inspect, lubricate, or repair the piston or other internalparts of the brake cylinder device it is necessary to remove the boltssecuring the casing to the journal box. When these bolts are removed,the release spring being under compression and acting on the piston willtend to throw the piston and cylinder away from the journal box and thuspossibly injure a workman. Furthermore, in order to mount the cylinderand piston on the journal box, it must be forced to its working positionagainst the tension of the release spring and this is not only diflicultfor a workman to do but it is also dangerous.

The principal object of the invention is therefore the provision of animproved brake cylinder device embodying means for limiting theexpansion of the release spring to a degree which will facilitateassembling and disassembling of the brake cylinder device and which willobviate possibility of injury to a workman during such operations.

Other objects and advantages will be apparent from the following moredetailed description of the invention.

In the accompanying drawing; Fig. l is a sectional view taken through awheel and journal box transversely of a railway vehicle truck andthrough a coaxially arranged disk brake mechanism embodying theinvention; and Fig. 2 is a stantially like that disclosed in theaforementioned Hewitt application and the following description thereofwill therefore be limited to only such details as are deemed necessaryto a clear and comprehensive understanding of the invention.

In the drawing, the reference numeral I indicates a wheel of a railwayvehicle truck having the usual flanged tread portion 2, a central hubportion 3 and an intermediate annular connecting web 4. The hub- 3 isrigidly connected to one end of a sleeve 5 which extends across thetruck and secures the two wheels of a wheel and axle assembly rigidly inspaced relation. Extending through the sleeve 5 is a normallynonrotating axle 5 which is supported at each of the opposite ends ofsaid sleeve in a roller bearing assembly comprising an outer race 1disposed in the open end of the tube 5 and an inner race 8 mounted onthe axle 6.

Encircling the axle 6 at the outboard face of wheel I and bearingagainst the end of axle tube 5 and the outer bearing race 1 is theflange 9of a brake ring l0. This flange is rigidly secured in positionby a plurality of torque bolts II which extend through and are rigidlysecured to the end of sleeve 5. Each of the torque bolts H is providedwith aportion l2 projecting in a direction away from the end of sleeve 5and disposed in a suitable bore in an outwardly extending part l3 of thebrake ring 10.

Disposed outboard of the wheel I is a journal box IE having a centralportion 16 and at' the inboard and outboard ends thereof flanges l1 andI8 respectively. The central portion 16 has a central opening in whichthere is disposed a sleeve l9 made of anti-friction material, such asbronze, and bearing on the extended end portion of axle B. The sleeve [9has at its inboard end an outwardly extending flange 20 between whichand the adjacent face of journal box flange I1 is interposed a pad 2!.The outboard end of the a sleeve is flanged inwardly over a shoulder 22provided on axle 6, this flange being indicated by the reference numeral23. Mounted over the end of the axle B and engaging the flange 23 is abacking plate 24. This plate overlaps the outboard flange [8 of thejournal box and a pad 25 is interposed therebetween.

The inboard end of sleeve l9 engages one side of a spacer ring 26 theopposite side of which engages one end of a shrink collar 21, said ringand collar being mounted on the axle 6. The opposite end of the shrinkcollar 21 in turn bears against the inner race 8 of the roller bearingwhich is disposed between the axle tube 5 and the normally non-rotatingaxle 6. A nut 28 is mounted on the outer end of axle 6 and hasscrew-threaded engagement therewith. This nut is screwed up against thebacking plate 24 which bears against the outboard end of sleeve 23. Byproper adjustment of this nut, therefore, the sleeve I9, spacer ring 26,and shrink collar 21 may be adjusted lengthwise of the axle 6 againstthe inner bearing race 8 for adjusting the roller bearing between theaxle tube 5 and axle 6. The nut 28 is adapted to be held in an adjustedposition on axle 6 by a key 29 fitting in suitably aligned slots 30provided in the outer face of the nut. The key 29 may be secured to theend of the axle 6 by cap screws 3|.

A rotatable brake disk or rotor 32 encircles the projecting part I2 ofthe torque bolts II and is provided around its inner peripheral edgewith suitable notches 33 in which the projecting portions I I of saidbolts are disposed for supporting said rotor and for turning same withthe wheel I. Both of the opposite radial faces of the rotor 32constitute friction braking surfaces and the adjacent surface on thewheel web 4 constitutes another friction brake surface.

Interposed between the wheel web 4 and adjacent face of the rotor 32 isan annular nonrotatable braking disk or stator 34, while disposed at theopposite face of rotor 32 is another annular non-rotatable braking diskor stator 35. These two stators and the interposed rotor are adapted tobe moved axially in the direction of wheel I into frictionalinterengagement to effect braking of said wheel and are adapted to bemoved in the opposite direction out of contact with each other to brakerelease positions, shown in the drawing, for releasing the brakes on thewheel. The means for holding the two stators against turning when infrictional contact with the rotor 32 and wheel web 4 and the means formoving said stators and the rotor 32 to their release positions shownare, for the sake of simplicity, not shown in the drawing.

For moving the brake elements axially into frictional engagement tobrake the wheel I a ring 31 is provided. This ring has an outer portionbetween which and stator 35 is interposed suitable spacers 38. The ringalso has an inner portion 39 encircling the flange 20 at the I inboardend of sleeve I9 and is provided with suitable stops 40 adapted toengage the inboard. flange I! of the journal box for limiting movementof the brake elements away from each other and for thereby definingtheir brake release positions.

Disposed beyond the outboard journal box flange I8 is a brake cylinderdevice arranged in coaxial relation with the normally non-rotatable axle6. The brake cylinder device comprises a body portion 42 havinginteriorly a piston bore 43 which at the outboard end of the bodyportion is closed preferably by an integrally formed pressure head 44.At the inner end of the body portion 42 there is provided an outwardlyextending annular web 45 connecting the body portion to a cylindricalportion 46 of greater diameter than said body portion. The portion 46extends in the direction of the journal box and is provided at itsinboard end with an annular outwardly extending flange 41. This flangeis mounted against a ring 48 which is secured by welding to the outboardjournal box flange I8. The ring 48 is provided with a plurality of screwthreaded bores aligned with suitable smooth Walled bores in the brakecylinder flange 41 and adapted to receive the screw threaded ends of capscrews 49 which are provided to rigidly secure the brake cylinder casingagainst the outboard'flange I8 of the journal box.

A brake cylinder piston 54 is slidably mounted in the piston bore 43 andis provided on its outer end with a cup-shaped packing 55 having a skirtportion 56 in sliding contact with the piston bore 43 for preventingleakage of fluid under pressure past the piston from a pressure chamber51 provided at the outboard face of the packing. The chamber 5'! isconnected to a brake cylinder pipe 58 through which fluid under pressureis adapted to be supplied to said chamber for acting on the piston tomove same in the direction of the wheel I for applying the brakes on thewheel and through which fluid under pressure is also adapted to bereleased to permit release of the brakes on the wheel.

The brake cylinder piston 54 is connected to the pressure ring 3! at theopposite end of the journal box by means of a plurality of struts orpins 63 which are spaced from each other around the sleeve I9 and whichextend through suitably aligned bores in flanges I I and I8 at theopposite ends of the journal box. The in-' board end of each of the pins60 is provided with a head BI which fits in a suitable recess providedin the inner portion 39 of the ring 31. A washer 62 on each of the pins60 bears against its head GI and overlaps the side of the recess inwhich said head is disposed and is welded to the ring 3'! therebysecuring the pin to the ring so that both will move together.

The opposite ends of the pins 60 are disposed in a chamber 63 formedwithin the cylindrical portion 46 of the brake cylinder casing.Extending into chamber 63 and overlapping the ends of pins 60, is anannular outward extension 64 of the brake cylinder piston. The extension64 is provided in its inboard face with a recess 65 for receiving theend of each of the pins 60, and adjacent the open end of this recesseach of the pins is provided with an annular groove 66. A retainingplate 61 is provided for securing the end of each of the pins 60 to theextension 64 of the brake cylinder piston. Each of these plates has aslot 68 to receive the reduced section of pin 60 at the bottom of thegroove 66 so as to thereby fit over the pin between the side walls ofsaid groove. At opposite sides of each pin the respective plate 61 isrigidly secured to the piston extension 64 by cap screws I0 so as tothereby secure the extended portion 64 of the brake cylinder piston tothe pins 69.

On the outer face of the brake cylinder piston packing 55 are provided aplurality of stops II which are adapted to engage the pressure head 44of the brake cylinder device at substantially the same time as the steps49 on ring 31 engage the inboard flange H on the journal box, either oneor the other or both of which are adapted to define the release positionof the ring 31 and thereby of the brake disks, above mentioned.

A release spring I2 encircling the nut 28 on the end of axle 6 andencircled by the brake cylinder piston 54 is provided for moving saidpiston and thereby the struts or pins 69 and ring 31 to their releasepositions upon the release of fluid under pressure from the pressurechamber 51.

The parts so far described may be substantially like similar parts ofthe truck and brake structure disclosed in the copending applicationhereinbefore referred to.

According to the invention I make the brake cylinder piston 54 in twoparts I and I6 which when assembled in the brake cylinder casing areadapted to abut in piston bore 43 at a line of division indicated by thereference numeral 11.

The inboard portion I6 of the brake cylinder piston has afrustro-conical shaped portion I8 extending into the interior of theoutboard portion I5 of said piston but not contacting same. At thesmaller end of the frustro-conical shaped portion 48 there is providedan inwardly extending annular flange 19 against which the outer end ofthe release spring I2 bears. It will be apparent that the pressure ofthe release spring applied to the flange I9 and transmitted therefromthrough the frustro-conical shaped portion I8 to the inboard part I6 ofthe brake cylinder piston and thence to the outboard part of the brakecylinder piston will move both of these parts to their brake releaseposition shown.

The inner end of the release spring 52 bears against a ring 80 whichencircles the nut 28 on the end of axle 6 and which engages the outboardface of the backing plate 24 and is thusv supported by the outboardflange !8 on the journal box. This ring extends beyond the spring I2 andto the outboard face of this extended part a plurality of bosses 8I aresecured by welding, these bosses being equally spaced from each otheraround the spring.

A bolt 82 extends through a suitable bore in each of the bosses 8| andhas an enlarged head portion 83 disposed in an opening in the ring ofgreater size than said bore so as to secure the bolts against pullingout of said ring. Each of these bolts extends from the ring 80 through asuitable bore provided in a wall 84 of a pocket 85 struck inwardly fromthe frustro-conical shaped portion I3 of the inboard part I6 of thebrake cylinder piston. In each pocket 85 a nut 86 is provided on the endof the bolt extending therein, this nut being slightly spaced from thewall 84 when the parts of the brake cylinder device are assembled, asshown in the drawing. With the several nuts 86 thus spaced from thewalls 84 it will be apparent that the release spring I2 is free to actto move the outboard part I5 of the brake cylinder piston, the inboardpart I6 of the brake cylinder piston and thereby the several struts orpins 60 and the ring 3! at the opposite end of the journal box to theirrelease positions shown.

When the brake cylinder piston 54 is moved in the direction of thejournal box I5 by fluid under pressure supplied to chamber 5I forefiecting an application of brakes on the wheel, this movement of bothparts of the brake cylinder piston and thereby of the walls 84 throughWhich the bolts 82 extend is relative to said bolts, said walls movingaway from the nuts 86. These bolts and the nuts 86 thus in no wayinterfere with the normal functioning of the brake cylinder device.

If a workman desires to inspect the interior of the brake cylinderdevice or to repair or clean and lubricate same, he removes the capscrews d3 securing the brake cylinder casing to the ring 48 which issecured to the outboard flange l8 of the journal box. He then pulls thebrake cylinder casing away from the journal box, the outboard portion I5of the brake cylinder piston remaining in the cylinder. Under thiscondition the brake cylinder release spring I2 is held in the samecompressed condition as when the brake cylinder casing is in place dueto the inboard portion I6 of the brake cylinder piston being connectedthrough the medium of the retaining plates 61 and pins 50 to the ring 31at the opposite end of the journal box, which ring is in contact throughthe medium of stops 40 with the inboard end of the journal box. Theparts of the brake cylinder device may then be inspected, cleaned, orrepaired as required and replaced in their operating positions withoutany interference from the release spring I2.

In initially applying the brake mechanism to the journal box I5 theseveral pins Bil are first secured to the ring 3? and then applied tothe journal box by threading said pins through the bores in the inboardand outboard flanges thereof.

Before mounting the inboard portion I5 of the brake cylinder piston inposition the release spring I2 is mounted therein against flange I9. Thering 86 having the bolts 82 applied thereto, is then mounted against theopposite end of the spring following which this assembly is placed in apress for moving the parts together. During this process the severalbolts 82 are threaded through the bores in the wall 84 of pockets 85.After a desired compression of the release spring 12 has been attained,the nuts 86 are applied to the ends of the bolts 82 and screwed upagainst the walls 84 for securing the spring in a predeterminedcompressed condition. This assembly is then removed from the press andwith the retaining plates (2! not yet applied to the outwardly extendingportion 64 of the brake cylinder piston the assembly is mounted over theends of the pins 58.

With the ring 3? at the inboard end of the journal box in its releaseposition shown and the inboard portion 56- of the brake cylinder pistoncontact with the nuts 86 the ends of the pins 59 will only enter therecesses in the outwardly extending part 64 of the piston to a slightextent but the degree of such entry i suiiicient to support this part ofthe brake cylinder piston on said pin. The retaining plates 3! are thenslipped into the grooves 65 and the cap screws iii are started into thepart 54 of the brake cyl nder piston and turned up against the retainingplates by hand. A wrench must then be applied to the cap screws Hi topull the plates 6"! and portion 84 of the brake cylinder piston intocontact. Thi contact is obtained by movement of the inboard part of thebrake cylinder piston in the d rection of the journal box reiative tothe pins 51 and during such movement the space shown in the drawingbetween the nuts 86 and the walls 34 is obtained to thereby insurefreedom. of the release spring I2 for moving the brake cylinder pistonto its release position.

It will now be apparent that the caging of spring 12 to a predeterminedlength under compression between the inboard part Iii of the brakecylinder piston and the ring 33 by means of bolts e2 will permit theready application of said part of the piston to the outer end of thestruts or pins =39 without any opposition from the spring. After thisassembly including the caged spring F2 is hung on the pins fill and thecap screws NJ are started by hand then and only then will the springbecome effective to oppose assembling of the brake cylinder piston toits operating condition, but such movement is readily eilected by awrench applied to the cap screws I6.

Summary It will now be apparent that the improved means for confiningthe brake cylinder release spring 72 before application to the brakecylinder device prevents interference of said spring in assembling anddisassembling the brake cylinder casing from the outboard flange it ofthe journal box and also facilitates the assembly of the various partsof the brake mechanism to the journal box. Further, the possibility ofinjury to a workman due to the release spring during such operations isobviated.

While only one illustrative embodiment of the invention has been shownand described in detail, it is not the intention to limit the scope tothat embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim a new and desire tosecure by Letters Patent is:

1. A fluid motor comprising a member, a casing mounted thereon, securingmeans removably securing said casing to said member, piston means insaid casing movable in the direction of said member under the action orfluid pressure, an element supported on said member, expansible springmeans interposed between said element and said piston means undercompression and operative upon release of fluid under pressure on saidpiston means to move same away from said member to the opposite end ofsaid casing, and adjustable means connecting said element to said pistonmeans and adjusted to limit movement of said piston means under theaction of said spring means to a degree no less than required to movesaid piston means to said opposite end of said casing but no greaterthan to provide for at least partial securing of said casing and membertogether by said securing means unopposed by said spring means.

2. A fluid motor comprising a member, a casing having one end in contactwith said member, screw means removably securing said casing and membertogether, piston means in said casing movable in the direction of saidmember under the action of fluid pressure, expansible spring meanshaving one end supported on said member and the opposite end acting onsaid piston means and operable upon release of fluid under pressure onsaid piston means to move same to the opposite end of said casing, andadjustable means connecting the one end of said spring means to theopposite end and adjusted to limit the expansion thereof to a degree noless than required to move said piston means to said opposite end ofsaid casing but providing for at least partial application of said screwmeans to said casing and member unopposed by said spring means.

3. A fluid motor comprising a member, a casing having one end in contactwith said member, screw means removably securing said casing and membertogether, piston means in said casing movable in the direction of saidmember under the action of fluid pressure, expansible spring meanshaving one end supported on said member and the opposite end acting onsaid piston means and operable upon release of fluid under pressure onsaid piston means to move same to the opposite end of said casing, anelement interposed between said member and the adjacent end of saidspring means, bolt means having one end fixed to said element and havinga sliding connection with said piston means providing for movementthereof in said casing, and means on said bolt means operative tocooperate with said piston means for limiting the expansion of saidspring means to a degree no less than required for moving said pistonmeans to said opposite end of said casing but providing for at leastpartial application of said screw means to said casing and memberunopposed by said spring means.

4. A fluid motor comprising a member, a casing having one end in contactwith said member, screw means removably securing said casing and membertogether, piston means in said casing movable in the direction of saidmember under the action of fluid pressure, expansible spring meanshaving one end supported on said member and the opposite end acting onsaid piston means and operable upon release of fluid under pressure onsaid piston means to move same to the opposite end of said casing, boltmeans having one end fixed with respect to said member and having asliding connection with said piston means providing for movement of saidpiston means in said casing relative to said bolt means, said bolt meansbeing adapted to cooperate with said piston means to limit the expansionof said spring means to a degree slightly exceeding that required formoving said piston means to said opposite end of said casing butproviding for at least partial application of said screw means to saidcasing and fixed member unopposed by said spring means.

5. A fluid motor comprising in combination a piston casing, a memberengaging one end of said casing, removable screw means securing saidmember and casing together, piston means in said casing adapted to bemoved by fluid under pressure in the direction'oi said member, springmeans interposed between said member and piston means and operable uponthe release of fluid under pressure on said piston means to move same inthe opposite direction to a position in substantial contact with saidcasing, an element interposed between one end of said spring means andsaid member, and adjustable means connecting said element to said pistonmeans providing for movement of said piston means in said casing andadjusted to limit expansion of said spring means to a degree no lessthan required for moving said piston means to said position insubstantial contact with said casing but no greater than to provide forat least partial application of said screw means to said casing andmember unopposed by said spring means.

6. A fluid motor comprising in combination a piston casing, a memberengaging one end of said casing, removable screw means securing saidmember and easing together, piston means in said casing adapted to bemoved by fluid under pressure in the direction of said member, springmeans interposed between said member and piston means and operable uponthe release of fluid under pressure on said piston means to move same inthe opposite direction to a position in substantial contact with saidcasing, and means for limiting the expansion of said spring means andthereby movement of said piston means relative to said member comprisingan element interposed between said member and the adjacent end of saidspring means, bolt means having one end secured to said element andhaving a slidable connection with said piston means providing formovement thereof in said casing, and means provided on the opposite endof said bolt means adapted to cooperate with said piston means to limitthe expansion of said spring means to a degree slightly exceeding thatrequired to move said piston means to said position but providing for atleast partial application of said screw means to said casing and memberunopposed by said spring means.

'7. A fluid motor comprising a casing, a member adapted to engage oneend of said casing, removable means securing said member and casingtogether, a rod slidably mounted in said member, piston means in saidcasing connected to one end of said rod and adapted to be operated byfluid under pressure to move said rod outwardly of said member forapplying brakes, spring means interposed between said member and pistonmeans and operable upon release of fluid under pressure on said pistonmeans to move same in a direction away from said member, means securingsaid rod to said piston means for rendering said spring means operableto move said rod with said piston means, means associated with said rodand cooperative with said member for limiting the degree of movement ofsaid rod and thereby of said piston means by said spring means, andmeans sup ported on said member and having a connection with said pistonmeans providing for operation of said piston means in said casing butoperative to limit the expansion of said spring means and therebymovement of said piston means to a degree which provides for at leastpartial securing of said rod to said piston means by the securing meansunopposed by said spring means.

8. A fluid motor comprising in combination a relatively fixed member, apiston casing mounted against one side of said member, screw meansremovably securing said casing and member together, a piston in saidcasing movable in the direction of said member by fluid under pressure,spring means interposed between said member and piston and operable uponthe release of fluid under pressure on said piston to move same in theopposite direction, a rod slidably mounted in said member, removablemeans securing the end of said rod adjacent said piston to said pistonfor movement therewith in both directions, means associated with theopposite end of said rod adapted to cooperate with said member forlimiting movement of said piston by said spring means, and means forlimiting the expansion of said spring means to a degree providing for atleast partial securing of said rod to said piston by said removablesecuring means unopposed by said spring means.

9. A fluid motor comprising a relatively fixed member, a piston casinghaving one end mounted against one face of said member, screw meansremovably securing said member and said casing together, piston means insaid casing adapted to be moved under the action of fluid pressure inthe direction of said member, spring means interposed between saidpiston means and member under compression and operable to move saidpiston means away from said member into substantial contact with theopposite end of said casing upon the release of fluid under pressure onsaid piston means, a rod slidably mounted in a bore in said member andhaving one end in contact with said piston means, screw means removablysecuring said one end of said rod to said piston means, means associatedwith the opposite end of said rod adapted to engage an opposite face ofsaid member at substantially the same time as said piston means movesinto contact with said casing, an element engaging said member andsupporting the adjacent end of said spring means, and means connectingsaid element to said piston means providing for movement of said pistonmeans against said spring means in the one direction, and intosubstantial contact with said casing in'the opposite direction, the lastnamed means being adapted to limit the expansion of said spring meansand thereby movement of said piston means in a direction away from saidmember to a degree which provides for the application and removal of thescrew means, securing said casing and member together, unopposed by saidspring means, and which also provides for at least partial applicationef the screw means securing said rod to said piston means also unopposedby said spring means.

10. A fluid motor comprising a relatively fixed member, a casing havingone end removably secured to said member and the opposite endconstituting a pressure head, a piston in said casing cooperating withsaid pressure head to form a chamber to receive fluid under pressure foracting on said piston to move same in the direction of said member, andspring means interposed between the opposite side of said piston andsaid member for urging said piston into substantial contact with saidpressure head upon the release of fluid under pressure from saidchamber, said piston comprising a cup shaped part adjacent said pressurehead and a ring-like part adapted to engage the peripheral edge of saidcup shaped part and having an inwardly extending part engaged by one endof said spring means, an element interposed between the opposite end ofsaid spring means and said member, and bolt means having a relativelyfixed connection with said element and a telescopic connection with saidinwardly extending part providing for movement of said piston means insaid casing but adapted to limit expansion of said spring means to adegree no less than required for movement of said piston into contactwith said pressure head but adapted to provide for at least partialapplication of said casing to said member unopposed by said springmeans.

11. A brake cylinder device comprising in combination with a relativelyfixed member a cup shaped casing having its open end mounted against oneface of said member, screw means removably securing said casing to saidmember, a piston slidably mounted in said casing and cooperating withthe closed end of said casing to form a pressure chamber adapted toreceive fluid under pressure for moving said piston in the direction ofsaid member for applying brakes, a coil spring having one end acting onsaid piston to move same in the opposite direction into substantialcontact with the closed end of said casing upon release of fluid underpressure on said piston, said piston comprising an inner cup shaped partdisposed adjacent the closed end of said casing and an outer ring-likepart adjacent the open end of said casing adapted to contact theperipheral edge of said inner part for transmitting the pressure offluid on said inner part to apply the brakes, the said outer part ofsaid piston having an inwardly extending part engaged by the said oneend of said spring, a ring supported on said member engaged by theopposite end of said spring, a plurality of bolts spaced around saidspring and having one end secured to said ring, said bolts extendingthrough bores in the said inwardly extending part of the said outer partof said piston providing for movement of said piston relative to saidbolts to its difierent positions, and a nut secured to each of saidbolts adapted to engage the said inwardly extending part of the saidouter part of the piston for limiting expansion of said spring to adegree providing at least for movement of said piston to its releaseposition and also providing for at least partial application of saidscrew means to said casing and member unopposed by said spring.

12. A brake cylinder device comprising in combination with a relativelyfixed member having two oppositely disposed and substantially parallelarranged flanges, a casing having an open end mounted against one ofsaid flanges and having an opposite closed end, screw means removablysecuring said casing to said one flange, a brake cylinder pistonslidably mounted in said casing and having at its outer end which is ad-J'acent the open end of said casing an outwardly extending annular part,a plurality of pins spaced from each other around a circle in coaxialrelation with said piston and slidably mounted in aligned bores throughthe said flanges and having their ends adjacent said piston aligned withsaid annular part of said piston, screw means removably securing theends of said pins to said annular part of said piston, stop meansassociated with the opposite ends of said pins adapted to cooperate withthe other of said flanges for defining a brake release position of saidpins. said piston being adapted to substantially engage the closed endof said casing to define its brake release position when said pins arein their brake release positions, a coil spring having one end acting onsaid piston for urging said piston and pins to their brake releasepositions, said piston being movable by fluid under pressure supplied.to act on its inner face in the direction of said one flange for movingsaid pins from their release positions through said flanges to effect anapplication of brakes, a ring disposed between said one flange and theopposite end of said spring, and means connecting said ring to saidpiston operative to limit expansion of said spring and thereby movementof said piston by said spring to a degree greater than required formoving said piston and pins to their brake release positions but whichprovides for at least partial application and removal of the screw meanssecuring said casing to said one flange unopposed by said spring andwhich also pro- 7 vides for at least partial application and removal ofthe screw means securing said pins to said piston also unopposed by saidspring.

JOSEPH C. McCUNE.

